From Legal Highs by The Twentieth Century Alchemist, published sometime in the 
early 1970's:

                        DANGEROUS COMBINATIONS

        Unless one is very experienced in pharmacology, it is unwise to 
experiment with combinations of drugs.  Even when using a single drug, thought 
should be given to all substances, both food and drug, which have been taken 
recently.  Most primitive people fast or at least abstain from certain 
substances for several days prior to taking a sacrament.  Substances most 
universally avoides are alcohol, coffee, meat, fat and salt.  Some drugs 
potentiate others.  For example, atropine will increase the potency of 
mescaline, harmine, cannabis and the opiates.  Many of the substances 
discussed in this book are MAO inhibitors.  MAO (monoamine oxidase) is and 
enzyme produced in the body which breaks down certain amines and renders them 
harmless and ineffective.  An MAO inhibitor interferes with the protective 
enzyme and leaves the body vulnerable to these amines.  A common substance 
such as tyramine, which is usually metabolized with little or no 
pharmacological effect, may become dangerous in the presence of an MAO 
innhibitor and cause headache, stiff neck, cardiovascular difficulties, and 
even death.  MAO inhibitors may intensify and prolong the effects of other 
drugs (CNS depressants, narcotic analgesics, anticholinergics, dibenzazepine 
antidepressants, etc.) by interfering with their metabolism.  In the presence 
of an MAO inhibitor many substances which are ordinarily non-active because of 
their swift metabolism may become potent psychoactive drugs.  This phenomenon 
may creat a new series of mind alterants.  However, because of the complex and 
precarious variables involved, it is risky and foolish for anyone to 
experiment with these possibilities on the non-professional level.
        The most commonly used MAO inhibitors include hydrazines such as 
iproniazid, Marsilid, Marplan, Niamid, Nardil, Catron; also non-hydrazines 
such as propargylamines, cyclopropylamines, aminopyrazine derivatives, 
indolealkylamines, and carbolines.  MAO inhibiting materials discussed in this 
book include yohimbine, various tryptamines, especially 5-MeO-DMT and the 
alpha-methyltryptamines, and the various harmala alkaloids.  The latter are 
especially potent inhibitors, but, like yohimbine and the tryptamines, are 
short-lasting in action (30 minutes to several hours).  Some of the commercial 
MAO inhibitors listed above are effective for several days to several weeks.
        Among the material which may be dangerous in combination with MAO 
inhibitors are sedatives, tranquilizers, antihistamines, narcotics and 
alcohol--any of which can cause hypotensive crises (severe blood pressure 
drop); and amphetamines (even diet pills), mascaline, asarone, nutmeg (active 
doses), macromerine, ephedrine, oils of dill, parsley or wild fennel, beer, 
wine, cocoa, aged cheeses and other tyrosine-containing foods (tyrosine is 
converted to tyramine by bacteria in the bowel)--any of which can cause 
hypertensive crises (severe blood pressure rise).